The Supreme Court has agreed to hear a case out of Wisconsin that could be a landmark in determining whether or not Republicans or Democrats have drawn their state’s electoral districts in a way that gives their candidates an unconstitutional advantage.

The case, Gill v. Whitford, comes to the court after a panel of three federal judges ruled 2-1 last year state lawmakers unconstitutionally drew the boundaries of state Assembly district lines to benefit Republicans in 2011. While the